The population tool GRAF-pop included in GRAF computes subject ancestries using genotypes and normalizes ancestry prediction in large datasets collected across different genotyping platforms, making it possible to generate population frequency based on more than a million dbGaP samples.

Who can use this?

GRAF is a tool for researchers; it is not designed to assess an individual’s ancestry or to find relatives.

You can use this tool against your own large datasets with results generated within hours or minutes, even when there is a very high genotype missing rate to the order of 99%. This tool can check genotype datasets obtained using different chips or platforms, plotting them in the same picture for comparison purposes.

Next Wednesday, June 27, 2018, we’ll introduce you to the Genetic Relationship and Fingerprinting (GRAF) software package. GRAF is a quality assurance tool that finds duplicates and closely related subjects in your data using SNP genotypes. We’ll also introduce the GRAF-pop feature, which computes subject ancestries and plots data for export as a .png or .txt file.

After registering, you will receive a confirmation email with information about attending the webinar. A few days after the live presentation, you can view the recording on the NCBI YouTube channel. You can learn about future webinars on the Webinars and Courses page.

Genome-wide association studies (GWAS) usually rely on the assumption that different samples aren’t from closely related individuals. If you’re using combined datasets that have been genotyped on different platforms, though, how do you detect duplicates and close relatives?

The dbGaP team at NCBI developed a new software tool and rapid statistical method called Genetic Relationship and Fingerprinting (GRAF) to do exactly that. At NCBI, we use GRAF as a quality assurance tool in dbGaP data processing. We’re presenting this tool publicly so any researcher can check the quality of their own data.

GRAF uses two statistical metrics to determine subject relationships directly from the observed genotypes, without estimating probabilities of identity by descent (IBD), or kinship coefficients, and compares the predicted relationships with those reported in the pedigree files. Please see the PLOS ONE article published in July 2017 for a detailed description of GRAF.

A recent update to GRAF adds the ability to determine subject ancestries. For more information on this addition, visit Poster #1322T, “Quickly determining subject ancestries in large datasets using genotypes of dbGaP fingerprint SNPs”, on Thursday, October 19th from 3-4 in the Exhibit Hall at ASHG.

About the NCBI

The National Center for Biotechnology Information (NCBI), a division of the U.S. National Library of Medicine, provides access to scientific and biomedical databases, software tools for analyzing molecular data, and performs research in computational biology.